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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b91f92659a5c30cd0604d49bacd4d73a02c0de8abfd82a5b1bdd1c7d1cb59016' 
  AND token = 'j+M92D25tkNemFwSCr7IsxNSr1huu5TT9TWmXWdAP9Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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