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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '779397c0b915ef02643910ca924d73e188c988613df54e915540fd65b46e8ff5' 
  AND token = 'TNcToUll3tGUiDxtSdEEJB/vLlLCCGCp8BJHCiOvW00=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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