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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a213000a3fce1ee621fd21eda77567767eee52564894e050e767dda51d27ea5' 
  AND token = 'U7jcsSU80aZPK1Nwvkya0726r2s45I8nVtDbyy0COtc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}