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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d6678d6e14f07ed71b6df7857a554cc1bb8b18883d249b37b09f01787b1ce36' 
  AND token = 'nzl03Qjruy25+QxUwBikowvimUif3W0DHVcvMb8EbaY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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