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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7bdf24d8680b2cb72cde19808e7a7747b4e49b633d0fedd38e7e5f3c5e439d9' 
  AND token = 'XMokjeEKMbKEvC3vqMbj7g9n+LPtFpuDAM56k9YtTAI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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