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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2357f8bd88ce1856ee71a1d5fd8765e4d5ae660ed57c6f2c04c8f818517b6f6a' 
  AND token = 'klmMg6y3AA6cdQ50kQgVj7Oa+z5nShoEmUjc9A2hN60=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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